Method for cleaning background areas from developed recording surfaces

ABSTRACT

Method and apparatus for forming images by providing an electrostatographic imaging member bearing an electrostatic latent image on a recording surface, developing the electrostatic latent image with a liquid developer comprising an insulating carrier liquid and suspended toner particles whereby at least a portion of the toner particles deposit on the recording surface to form an imaged recording surface having image areas and background areas, and contacting the imaged recording surface with a film of cleaning liquid carried on the surface of an applicator member to remove toner particles deposited in the background areas.

United States Patent [191 Takahashi et al.

[ METHOD FOR CLEANING BACKGROUND AREAS FROM DEVELOPED RECORDING SURFACESlsoji Takahashi; Masamichi Sato, both of Asaka, Japan Assignee: RankXerox, Ltd., London, England Filed: Nov. 27, 1970 Appl. No.: 93,313

Inventors:

[30] Foreign Application Priority Data Dec. 2, 1969 Japan 44-96397 U.S.Cl. 117/37 LE, 96/1 LY, 134/122, 355/10, 355/15 Int. Cl. G03g 13/10,603g 13/22 Field of Search 117/37 LE; 96]] LY; 118/637, DIG. 23; 355/10,15; 134/122 References Cited UNlTED STATES PATENTS 6/1959 Bolton 117/37LE 5/1960 Bolton et a1...

6/1962 Johnson 118/637 [451 Nov. 19, 1974 3,247,007 4/1966 Oliphant117/37 LE 3,276,896 10/1966 Fisher 117/37 LE 3,356,498 12/1967 Moe eta1... 117/37 LE 3,367,791 2/1968 Lein 117/37 LE 3,368,526 2/1968Matsumoto et a1 117/37 LE 3,372,027 3/1968 Gundlach et al. 117/37 LE3,384,051 5/1968 Hunstiger 117/37 LE 3,419,411 12/1958 Wright 117/37 LE3,577,259 5/1971 Sato et a1 117/37 LE Primary Examiner-MichaelSofocleous [5 7] ABSTRACT Method and apparatus for forming images byproviding an electrostatographic imaging member bearing an electrostaticlatent image on a recording surface, developing the electrostatic latentimage with a liquid developer comprising an insulating carrier liquidand suspended toner particles whereby at least a portion of the tonerparticles deposit on the recording surface to form an imaged recordingsurface having image areas and background areas, and contacting theimaged recording surface with a film of cleaning liquid carried on thesurface of an applicator member to remove toner particles deposited inthe background areas.

19 Claims, 3 Drawing Figures PATENIUV 191914 INVENTORS ISOJI TAKAHASHIMASAMICHI SATO ATTORNEY METHOD FOR CLEANING BACKGROUND AREAS FROMDEVELOPED RECORDING SURFACES BACKGROUND OF THE INVENTION This inventionrelates to imaging systems, and more particularly, to an improved methodand apparatus for developing electrostatic latent images with a liquiddeveloper.

Processes for the formation and the development of images on the surfaceof photoconductive materials by electrostatic means are well known.These processes include dry techniques such as cascade, powder cloud andmagnetic brush processes and wet techniques such as the liquiddevelopment process. One conventional liquid development processinvolves placing a uniform electrostatic charge on a photoconductiveinsulating layer comprising zinc oxide power and a resinous bindercarried on a conductive paper substrate, exposing the layer to a lightand shadow image to dissipate the charge on the areas of the layerexposed to the light and developing the electrostatic latent image bydepositing on the image a charged toner which is dispersed in aninsulating liquid. The charged toner may be suitably colored and mayhave a polarity of charge identical with or opposite to that of thelatent image to be developed. If the polarity or charge of the toner isidentical to that of the latent image, reversal development will occurwhereas a toner having a charge opposite to that of the latent imagewill be attracted to the latent image.

Although considered a highly desirable technique for the formation ofimages, difficulties are encountered with attempts to form high qualityimages with the liquid development process. Generally, liquiddevelopment is effected by either immersing the electrostatic latentimage bearing surface into the liquid developer or contacting the imagebearing surface with a uniform film of liquid developer carried on anapplicator surface. The liquid developer adhering to the imaging surfaceis thereafter dried by mere exposure to ambient air at room temperature,circulating heated air, infrared heating, pressure from squeegee rollersor the like. Unfortunately, the liquid developer adhering to thebackground areas of the imaging surface contain toner particles whichremain on the imaging surface after drying. These undesirable backgrounddeposits are particularly acute in high speed continuous tonedevelopment systems employing a liquid developer containing highconcentrations of toner particles.

In multicolor processes, where the development process is repeated withdifferent colored developers corresponding to the primary colors to forma colored print on a single photosensitive surface, it is highlydesirable that the charging and discharging properties of thephotosensitive layer remain substantially unaffected by the presence ofa toner image previously formed on the photosensitive layer. Generally,with conventional liquid development processes, the fixing agent,stabilizer, electric charge regulator and the like which are employed inliquid developer remain on the photosensitive layer after developmentand tend to deteriorate the photoreceptor properties thereby inhibitingthe proper formation of subsequently developed images.

It has been found that uniform photoreceptor properties can bemaintained and background toner deposits can be reduced by immersing theimaging surface immediately after development in a rinsing liquid whichcontains little or no toner particles or other contaminants. However,the rinsing liquid rapidly becomes ineffective due to the accumulationof toner particles and other undesirable materials found in liquiddevelopers. In addition, a rinsing step presents additional problems inhigh speed development systems because treatment time and equipmentcomplexity is increased. In addition, as a result of increasing tonercontaminants in the rinsing liquid, additional equipment is required toremove these contaminants.

In addition to mere dipping of a developed imaging surface into a tonerfree cleaning liquid, one could attempt to remove toner from thebackground areas of a developed surface by injecting a cleaning liquidagainst the developed surface. This method comprises drawing up acleaning liquid with means such as a pump and projecting it against thedeveloped surface so as to wash away the liquid developer adhering tothe developed surface. Although this washing method is effective, it isdeficient in that equipment complexity and the space required for itsinstallation are increased. In addition, this method requires the use ofa hoze, nozzle, and a liquid pump further complicating the washingoperation. Also, maintenance of the washing equipment proves to beparticularly troublesome. Since most liquid development techniques aredeficient in one or more of the above areas, there is a continuing needfor improving imaging processes.

SUMMARY OF THE INVENTIO It is therefore an object of this invention toprovide an imaging system overcoming the above noted deficiencies.

It is another object of this invention to provide an imaging techniquewhich improves electrostatographic image quality.

It is a further object of this invention to provide images havingreduced background deposits.

It is still another object of this invention to provide an imagingsystem which removes contaminants more effectively from imagingsurfaces.

It is another object of this invention to provide an imaging systemsuperior to those of known systems.

The above objects and others are accomplished in accordance with thisinvention, generally speaking, by providing an electrostatographicimaging member bearing an electrostatic latent image on a recordingsurface, developing the electrostatic latent image with a liquiddeveloper comprising an insulating carrier liquid and suspended tonerparticles whereby at least a portion of the toner particles deposit onthe recording surface to form an imaged recording surface having imageareas and background areas, and contacting the imaged recording surfacewith a film of cleaning liquid carried on the surface of an applicatormember to remove toner particles deposited in the background areas.Mechanically, only the cleaning liquid film is permitted to come intocontact with the developed surface. Accordingly, the developed imagewill not be damaged or destroyed. Further, the cleaning can beaccomplished in a very short period of time because the cleaning liquidfilm may be contacted with the developed surface at a high rate ofspeed.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages of the improvedelectrostatographic imaging systems will become further apparent uponconsideration of the following disclosure of the invention, particularlywhen taken in conjunction with the accompanying drawings wherein:

FIG. 1 is a schematic sectional view in which an electrostatographicimage is cleaned by immersion in a cleaning liquid.

FIG. 2 is a schematic sectional view of an electrophotographic imagingapparatus employing an embodiment of the cleaning system of thisinvention.

FIG. 3 is a schematic sectional view of an alternative form of theapparatus shown in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The conventional technique toremove toner parti cles from the background areas of a developedelectrostatographic recording member by immersion in a toner-freecleaning liquid is illustrated in FIG. ll. Reference characterdesignates a toner image formed by conventional liquid developmenttechniques on a photoreceptor sheet 11. Removal of excess tonerparticles 12 deposited on the front and rear surfaces of thephotoreceptor sheet 11 is effected by immersing the photoreceptor sheet11 in cleaning liquid 13. During immersion, various components such asfixing agents, stabilizers and electric charge regulators originatingfrom the liquid developer are also removed from the photoreceptor sheet11 by cleaning liquid 13. It is apparent, that the cleaning liquidemployed in this cleaning system is most efficient when freshuncontaminated cleaning liquid is employed. Obviously, the cleaningliquid should be selected from liquids which will not destroy the tonerimage or dissolve and swell the photorecepter sheet 11. It is furtherapparent, that the cleaning liquid is preferably a liquid which ishighly insulating and has a low dielectric constant. Although thecleaning process described with reference to FIG. 1 reduces backgrounddeposits in developed images, it requires a time consuming operation andis difficult to automate.

In FIG. 2, a photoreceptor sheet 14 bearing a developed surface on thelower side thereof is delivered by means of a guide roller 15 foradvancing the photoreceptor sheet 14 in a fixed path. Referencecharacter 16 denotes a roller adapted to rotate at a high rate of speed,with the lower part thereof submerged in fresh, clear cleaning liquid 17which is contained in reservoir 18. Obviously, cleaning liquid 17 shouldcontain little or no toner particles or other contaminants and shouldhave a lower concentration of developer particles than the liquiddeveloper employed to develop photoreceptor sheet 14 and shouldpreferably be substantially free of any developer particles for mostefficient cleaning results. Cleaning liquid 17, of course, also shouldbe selected from those materials which will not swell or dissolve thephotoreceptor sheet 14 or the toner image. For example, ifphotosensitive paper comprising zinc oxide and an insulating binderlayer is employed, cyclohexane, hexane, heptane, or petroleum solventssuch as isoparaffin or gasoline may be used. If desired, a suitableamount of chlorinated hydrocarbon or fluorinated hydrocarbon may beadded to the cleaning liquid to render the cleaning mixture lessflammable. As roller 16 rotates at a high rate of speed, a film ofcleaning liquid 19 is formed on the peripheral surface thereof. Oncethis film of liquid is formed, it acquires a constant rate of rotationand rotates in conjunction with the roller. Upon contact of cleaningliquid film 19 with photorecepter sheet 14, cleaning liquid film 19thereby washes away excess toner particles along with it. However, as aconsequence, the same film of cleaning liquid remains around the rollerand soiling of the cleaning liquid film becomes intensive. Therefore, abaffle plate 20 is disposed below roller 16 so as to insure desirablecirculation of the cleaning liquid film in the cleaning liquid vessel.This circulation serves to permit all of the cleaning liquid inreservoir 18 to become soiled uniformly, with the aforementioneddrawback eliminated thereby. The circulation of the cleaning liquid neednot always be accomplished by means of such baffle plate or blade. Othersuitable circulation methods, such as agitation with a stirrer, may beused for the purpose. Since photoreceptor sheet 14 is cleaned with asubstantially uncontaminated cleaning liquid, maximum removal of excesstoner particles and other undesirable developer components is effected.Further, it is apparent that cleaning liquid 17 can be repeatedlyemployed to clean photoreceptor sheet 14 because the film iscontinuously replenished from the cleaning liquid containing a very lowconcentration of developer components.

The cleaning step of this invention should be carried out before thedeveloped photoreceptor sheet 14 is allowed to dry. Poor results areobtained when removal of background toner deposits is attempted afterthe developed photoreceptor sheet 14 is permitted to dry completely.

The thickness of film 19 of cleaning liquid 17 varies with the viscosityof cleaning liquid 17 and the peripheral speed of roller 16. The filmthickness increases with increasing viscosity of the cleaning liquid andgenerally with an increasing rate of rotational speed of roller 16.Satisfactory results are achieved with a film thickness in the range offrom about Va millimeter to about 3 millimeters.

The cleaning effect of film 19 is decreased where the thickness of film19 is too small. To increase the cleaning speed, it is generallysufficient to increase the rotational speed of roller 16. However, ifthe rotational speed of roller 16 is increased excessively, film 19adhering to roller 16 may be drawn away from roller 16 by virtue ofcentrifugal force, also the developed toner image may consequently bedamaged or destroyed. Therefore, the upper limit of the rotational speedof roller 16 is determined by the nature of the developed image. Wherethere is firm adhesion between the developed toner image and thephotoreceptor surface, safe cleaning can be accomplished if the relativespeed of the developed surface and the film of cleaning liquid increasesto a level of about 30 meters per second. Thus, safe cleaning may beaccomplished where the film of cleaning liquid contacts the developedsurface at a relative rate of speed greater than that of the developedsurface. Where the adhesive force of the toner image to thephotoreceptor surface is small, there may be cases in which the relativespeed is preferably limited to a level of about 30 centimeters persecond. It

should be apparent that when contact is made if there I is substantiallyno difference in the rate of speed between the film of cleaning liquidand the developed surface less efficient cleaning of the developedsurface is obtained. For example, if both the film of cleaning liquidand the developed surface are traveling in the same direction and atsubstantially the same rate of speed,

cleaning efficiency decreases. Cleaning efficiency increases where thedeveloped surface is moving slowly in one direction, for example,clockwise, and the film of cleaning liquid is moving in anotherdirection, for example, counterclockwise, Maximum cleaning efficiency isobtained as the rate of speed of the developed surface is increased inone direction, for example, clockwise, with the rate of speed of thefilm of cleaning liquid increased in another direction for example,counterclockwise.

Another specific embodiment of the cleaning system of this invention isillustrated in FIG. 3. In this embodiment, shielding plates 21 and 22are disposed for the purpose of preventing cleaning liquid film 19 frombeing dispersed randomly by virtue of centrifugal force when roller 16rotates at a high rate of speed. Shielding plates 21 and 22 consequentlyprevent the cleaning liquid from being dispersed randomly and permit theselection of a suitable opening with roller 16 so as to control thethickness of liquid film being rotated since liquid film adhering to theroller may be sent flying by virtue of centrifugal force and thedeveloped toner image may be damaged or destroyed. Although therotational direction of roller 16 carrying the cleaning liquid thereonis opposite to that of roller carrying the photoreceptor sheet in thedescription of FIG. 2 and FIG. 3, it can be in the same direction.Higher relative speeds, however, and consequently higher cleaning ratesare achieved with countercurrent contact.

After repeated use, the cleaning liquid becomes increasingly soiled.However, suitable recovery techniques can be used. For example, thetoner material can be removed electrically, and the resinous componentdissolved therein can be removed such as by means ofa desorbent. Thus,in the system of this invention, the background toner deposits andsoluble liquid developer components which adhere to the surface of anelectrostatographic imaging member are washed away by substantiallyfresh clean cleaning liquid. It is apparent from the foregoingdescription that consumption of cleaning liquid is reduced to a minimumand contamination of the cleaning liquid does not significantly impedecleaning effectiveness. Further, the

equipment required is quite simple and compact, the space necessary forits installation is small and both operation and maintenance areminimal.

Any suitable material, such as conventional binder plates, may beemployed in the photoreceptor sheet of this invention. Preferably, thematerial should resist dissolving or swelling when contacted with theliquid developer and the cleaning liquid. For example, whilephotosensitive paper comprising zinc oxide and an insulating binderlayer are discussed above, it is to be understood that other imagingmembers may be employed and that the choice of particular imaging memberand particular development system may be readily determined by oneskilled in the art. For example, cadmium sulfide, zinc sulfide, zincselenide, cadmium selenide, titanium dioxide, phthalocyanine andpolyvinyl carbazole may be employed as a photoconductive material. inaddition, other suitable electrostatographic imaging members may beemployed.

Any suitable conventional insulating liquid developer may be employed inthe system of this invention. Typical liquid developers containelectroscopic marking particles dispersed in an insulating liquidvehicle and may also contain control agents and suspending agents fortheir well known functions. The electroscopic marking particles areconventionally dispersed and suspended in the liquid by stirring oragitation and where a highly uniform and stable suspension is desired,the suspension may be passed through a colloid mill. For optimumresults, toner particles having an average diameter of less than about 1micron are preferred because higher resolution images and more stabledeveloper mixtures are achieved.

Although specific materials and conditions are set forth in theforegoing examples, these are merely intended as illustrations of thepresent invention. Various other suitable electrostatographic imagingmembers, developers, cleaning liquids and cleaning system configurationsincluding those listed above may be substituted for those in thespecific examples with similar results. For example, various othersuitable applicator members such as an endless belt of metal, rubber,plastic, cloth, or paper may be used. Other materials may also be addedto the imaging member, developer, or cleaning liquid to sensitize,synergize or otherwise improve the imaging properties or desirableproperties of the system.

Other modifications of the present invention will occur to those skilledin the art upon a reading of the present disclosure. These are intendedto be included within the scope of this invention.

What is claimed is:

l. A method of forming images comprising providing anelectrostatographic imaging member bearing an electrostatic latent imageon a recording surface, developing said electrostatic latent image witha liquid developer comprising an insulating carrier liquid and suspendedtoner particles whereby at least a portion of said toner particlesdeposit on said recording surface to form an imaged recording surfacehaving image areas and background areas, rotating an applicator memberin a cleaning liquid to form a film of said cleaning liquid on thesurface of said applicator member, maintaining said applicator memberfree from contact with said imaged recording surface, and contactingsaid imaged recording surface with said film of cleaning liquid carriedon the surface of said applicator member to remove toner particlesdeposited in said background areas.

2. A method according to claim 1 including removing said film ofcleaning liquid contaminated with said toner particles from said surfaceof said applicator member.

3. A method according to claim 2 including recovering said film ofcleaning liquid contaminated with said toner particles removed from saidsurface of said applicator member.

4. A method according to claim 3 including dispersing said film ofcleaning liquid contaminated with said toner particles in a cleaningliquid bath to circulate at least a portion of said contaminated filmand forming a new film of cleaning liquid on said surface of saidapplicator from substantially uncontaminated cleaning liquid for furthertreatment of imaged recording surfaces.

5. A method according to claim 4 including stirring said film ofcleaning liquid contaminated with said toner particles in a cleaningliquid bath to circulate at least a portion of said contaminated filmand forming a new film of cleaning liquid on said surface of saidapplicator from substantially uncontaminated cleaning liquid for furthertreatment of imaged recording surfaces.

6. A method according to claim including reforming said film of cleaningliquid on said surface of said applicator member with recirculatedcleaning liquid for further treatment of said imaged recording surfaces.

7. A method according to claim 1 including removing said toner particlesdeposited in said background areas substantially immediately afterdeveloping said electrostatic latent image.

8. A method according to claim 1 including transporting said film ofcleaning liquid in an arcuate path to said imaged recording surface.

9. A method according to claim 1 including regulating the thickness ofsaid film of cleaning liquid carried on said surface of said applicatormember prior to contact with said imaged recording surface.

10. A method according to claim 9 including maintaining said thicknessof said film of cleaning liquid carried on said surface of saidapplicator member prior to contact with said imaged recording surface inthe range of from about 1% millimeter to about 3 millimeters.

11. A method according to claim 1 including reducing the thickness ofsaid film of cleaning liquid carried on said surface of said applicatormember prior to contact with said imaged recording surface.

12. A method according to claim 1 including contacting said imagedrecording surface with a film of cleaning liquid carried on said surfaceof said applicator member sufficiently thick to remove at least aportion of said toner particles deposited in said background areas.

13. A method according to claim 1 including advancing an imagedrecording surface in a fixed path and advancing said film of cleaningliquid carried on said surface of said applicator member in a directioncountercurrent to said imaged recording surface.

14. A method according to claim 1 including contacting said imagedrecording surface with said film of cleaning liquid carried on saidsurface of said applicator member and traveling at a relative rate ofspeed greater than said imaged recording surface.

15. A method according to claim 1 including contacting said imagedrecording surface with said film of cleaning liquid carried on saidsurface of said applicator member and traveling at a relative rate ofspeed between about 30 centimeters per second and about 30 meters persecond.

16. A method of surface cleaning developed electrostatographic recordingsurfaces comprising providing a recording member having an imagedrecording surface bearing toner particles deposited in image areas andbackground areas, applying a film of cleaning liquid to the surface ofan applicator member, transporting said imaged recording surface into acleaning zone located outside a development zone, and contacting saidimaged recording surface with said film of cleaning liquid carried onsaid surface of said applicator member to remove said toner particlesdeposited in said background areas.

17. A method according to claim 16 including contacting said imagedrecording surface with said film of cleaning liquid carried on saidsurface of said applicator member and traveling at a relative rate ofspeed greater than said imaged recording surface.

18. A method according to claim 16 including disposing shielding platesadjacent to and spaced away from said applicator member and adapted toprevent said film of cleaning liquid from being dispersed randomly byvirtue of centrifugal force when said applicator member rotates at ahigh rate of speed.

19. A method according to claim 16 including disposing shielding platesadjacent to and spaced away from said applicator member and adapted tocontrol the thickness of said film of cleaning liquid being rotated. =i

1. A METHOD OF FORMING IMAGES COMPRISING PROVIDING ANELECTROSTATOGRAPHIC IMAGINING MEMBER BEARING AN ELECTROSTATIC LATENTIMAGE ON A RECORDING SURFACE, DEVELOPING SAID ELECTROSTATIC LATENT IMAGEWITH A LIQUID DEVELOPER COMPRISING AN INSULATING CARRIER LIQUID ANDSUSPENDED TONER PARTICLES WHEREBY AT LEAST A PORTION OF SAID TONERPARTICLES DEPOSIT ON SAID RECORDING SURFACE TO FORM AN IMAGES RECORDINGSURFACE HAVING IMAGE AREAS AND BACKGROUND AREAS, ROTATING AN APPLICATORMEMBER IN A CLEANING LIQUID TO FORM A FILM OF SAID CLEANING LIQUID ONTHE SURFACE OF SAID APPLICATOR MEMBER, MAINTAINING SAID APPLICATORMEMBER FREE FROM CONTACT WITH SAID IMAGED RECORDING SURFACE, ANDCONTACTING SAID IMAGED RECORDING SURFACE WITH SAID FILM OF CLEANINGLIQUID CARRIED ON THE SURFACE OF SAID APPLICATOR MEMBER TO REMOVE TONERPARTICLES DEPOSITED IN SAID BACKGROUND AREAS.
 2. A method according toclaim 1 including removing said film of cleaning liquid contaminatedwith said toner particles from said surface of said applicator member.3. A method according to claim 2 including recovering said film ofcleaning liquid contaminated with said toner particles removed from saidsurface of said applicator member.
 4. A method according to claim 3including dispersing said film of cleaning liquid contaminated with saidtoner particles in a cleaning liquid bath to circulate at least aportion of said contaminated film and forming a new film of cleaningliquid on said surface of said applicator from substantiallyuncontaminated cleaning liquid for further treatment of imaged recordingsurfaces.
 5. A method according to claim 4 including stirring said filmof cleaning liquid contaminated with said toner particles in a cleaningliquid bath to circulate at least a portion of said contaminated filmand forming a new film of cleaning liquid on said surface of saidapplicator from substantially uncontaminated cleaning liquid for furthertreatment of imaged recording surfaces.
 6. A method according to claim 5including reforming said film of cleaning liquid on said surface of saidapplicator member with recirculated cleaning liquid for furthertreatment of said imaged recording surfaces.
 7. A method according toclaim 1 including removing said toner particles deposited in saidbackground areas substantially immediately after developing saidelectrostatic latent image.
 8. A method according to claim 1 includingtransporting said film of cleaning liquid in an arcuate path to saidimaged recording surface.
 9. A method according to claim 1 includingregulating the thickness of said film of cleaning liquid carried on saidsurface of said applicator member prior to contact with said imagedrecording surface.
 10. A method according to claim 9 includingmaintaining said thickness of said film of cleaning liquid carried onsaid surface of said applicator member prior to contact with said imagedrecording surface in the range of from about 1/3 millimeter to about 3millimeters.
 11. A method according to claim 1 including reducing thethickness of said film of cleaning liquid carried on said surface ofsaid applicator member prior to contact with said imaged recordingsurface.
 12. A method according to claim 1 including contacting saidimaged recording surface with a film of cleaning liquid carried on saidsurface of said applicator member sufficiently thick to remove at leasta portion of said toner particles deposited in said background areas.13. A method according to claim 1 including advancing an imagedrecording surface in a fixed path and advancing said film of cleaningliquid carried on said surface of said applicator member in a directioncountercurrent to said imaged recording surface.
 14. A method accordingto claim 1 including contacting said imaged recording surface with saidfilm of cleaning liquid carried on said surface of said applicatormember and traveling at a relative rate of speed greater than saidimaged recording surface.
 15. A method aCcording to claim 1 includingcontacting said imaged recording surface with said film of cleaningliquid carried on said surface of said applicator member and travelingat a relative rate of speed between about 30 centimeters per second andabout 30 meters per second.
 16. A method of surface cleaning developedelectrostatographic recording surfaces comprising providing a recordingmember having an imaged recording surface bearing toner particlesdeposited in image areas and background areas, applying a film ofcleaning liquid to the surface of an applicator member, transportingsaid imaged recording surface into a cleaning zone located outside adevelopment zone, and contacting said imaged recording surface with saidfilm of cleaning liquid carried on said surface of said applicatormember to remove said toner particles deposited in said backgroundareas.
 17. A method according to claim 16 including contacting saidimaged recording surface with said film of cleaning liquid carried onsaid surface of said applicator member and traveling at a relative rateof speed greater than said imaged recording surface.
 18. A methodaccording to claim 16 including disposing shielding plates adjacent toand spaced away from said applicator member and adapted to prevent saidfilm of cleaning liquid from being dispersed randomly by virtue ofcentrifugal force when said applicator member rotates at a high rate ofspeed.
 19. A method according to claim 16 including disposing shieldingplates adjacent to and spaced away from said applicator member andadapted to control the thickness of said film of cleaning liquid beingrotated.